Disk brake construction



June 23, 1953 P. M. FREER 2,542,959

' DISK BRAKEV CONSTRUCTION l Filed oct. 23. 194e 5 sheets-sheet 1 P. M.FREER DISK BRAKE CONSTRUCTION June Z39 1953 med oct. 23. '1948' A 5Sheets-Sheet 2 June 23, 1953 v l P, M. FREE-:R i 2,542,959

' DISK BRAKFJ coNsTRUcT'IoN Filed oct. 25. 1948 5 sheets-sheet 3 f (ma)IN VEN TOR. PdJ/s M' /T/ee/f Hfranwfy?.

June 23, 1953 j P.-.M. FREER 2,642,959

DISK BRAKE CONSTRUCTIONl Filed oct. 2s. 1948 s'sheets-sheet 4 ma/WVEYSJJune 23, 1953 P., M. FREER DISKY BRAM? CONSTRUCTION Filed Oct. 23, 19485 Sheets-Sheet 5 INVENTOR. 7' 64145 M 7729er 2 ffm f WA/EKF,

Patented June 23, 1953 tusse UNITED sTATss eATsNT oFFIcs 2,642,959 msnBRAKE ooNs'rRUoTIoN Phelps M. Freer, Detroit, Mich. applicati@ october2s, 1948, serial No. 56,085

(c1. iss-i2) 1S Claims.

This invention relates to braking devices in general but refers inparticular to an improved disc brake construction.

It is notable that disc brakes have not been accepted by the automotiveindustry, in spite of the fact that they have certain inherentadvantages from the standpoint of actual operation and performance overthe conventional band type brakes. There are two principal reasons forthis failure of the disc type'bra'ke to receive widespread application;first, the high cost of manufacture, and second, the relatively shortlife of the brake lining due to the W rate of heat dissipation.

lt is the purpose of the present invention to eliminate the foregoingobjections tofdisc type brakes and to provide certain other desirablefeatures of construction. In contrast to disc brakes heretofore known,the brake of the present invention is exceedingly simple and inexpensiveto manufacture. No machining is required to form the component partsand, in assembly, these parts Y simply rit together with only a fewrivet and weld connections required. The second objection to disc brakesis eliminated in two ways. First, by the provision of a brakeconstruction which includes a cooling system whereby a suitable coolantsuch as air may carry away suicient/ heat to materially reduce brakingtemperatures and thereby prolong the life of the brake linings.

Second, by the provision of a braking member to engage the brake shoewhich is of a construction which interrupts the generation of frictionalheat and which has a large area for radiating the heat developed and alarge'volurne ior absorbing heat developed. As an'added feature ofconsiderable practical importance, the invention provides a brakeconstruction which is Yself-adjusting to compensate for Wear oi thebrakev lining. A further feature which makes the brake particularlydesirable for modern automobiles in which a minimum-size brake isdesired, is the high brakn ingV capacity of the present design whichmakes it possible to provide a highly effective brake which occupiesonly a small and compact space.

Various features of the invention may be employed in other types ofbrake construction as those in the art will realise after considerationof the accompanying drawings showing it embodiedv in a disc brakewherein:

Figure l is a side elevation of one form of disc brake constructionembodying the invention taken from the inboard side thereof, the brakebeing shown as it would appear inA a vertical section through anautomobile axle;v

Fig. 2 is an axial section taken on the line 2-2 of Fig. 1;

Fig. 3 is a lateral section taken on the line 3 3 of Fig. 2 illustratingone form of wear compensating means;

Fig. 4 is a side elevation of the construction heretofore illustratedtaken from the outboard side thereof with the coolant i'low impellerpartially broken away as viewed'irom line iof Fig. 2;

Fig. 5 is a radial section taken on line 5--5 of Fig. 4;

Fig. 6 is a detail plan View of the pressure disc employed in theconstruction illustrated;

Fig. '7 is a section taken on the line 'i-l of Fig. 6;

Fig. '7A shows a modified form oi means for rotating the cam ring;

Fig. 8 is a detail plan view of the inboard disc which cooperates withthe pressure disc of Fig. 6;

n Fig. 9 is a diametrical section taken on the line 9 9 of Fig. 8;

Fig. 10 is an endelevation of a portion of the inboard disc as observedfrom line lt-I of Fig. 8;

. Fig. 11 is a detail plan view of the mounting sleeve;

Fig. l2 is a section taken on line i2-i2 ci Fig. ll'g' Fig. 13 is a sideelevation of the parking brake attachment used with the hereindescribedbrake construction; and,

Figs. 14 and 15 are radial sections taken on, the lines ill- I4 and l-lof Figvl;

Fig. 16 is a plan view of the brake disc and impeller assembly as takenfrom line it-ii of Fig. 14;

AFig. l'l' is a view.' taken on line l'i-i'i of Fig. 2 showing thereturn springs;

` Fig. 18l is a vieuT taken on line S8448 of Fig. 2 showing the ratchetmeans;

Fig.l19 is a. view taken on line i-i of Fig. l5 showing the structureenabling the braie to he used fora parking brake; and

Fig. 20 is a schematic diagram ci the mode oi' operation of the lingers99 which rotate the cam plate 3l to maintain constant slack clearance.

' Referring first to Figs. 2, ll, and l2 of the drawings, it will be'observed that the inner member -3 forms the mounting and supportmeans-for 'the rotary disc brake which will be generally designated bythe reference numeral I. The support member 3, or mounting sleeve,

55 as it is referred to in practice, is broadly hatshaped in appearance,having a crown 5 with a large axial aperture 1 therein and a flange 8.The crown end of the sleeve 3 may be provided with a plurality ofapertures 9 surrounding aperture 1 by means of 1which fixed connectionwith an automobile chassis, for example, may be achieved through themedium of bolts, rivets, or the like. The outer periphery of the crown 5is adapted to prevent rotation of some members mounted thereon whilepermitting rotation of others. A preferred method of accomplishing thisconsists in forming the crown so that it is noncircular in crosssection, the substantially hexagonal shape illustrated in Fig. 11 'beingsuitable. The flat sides l of the hexagon prevent rotation of membersfitted thereto `while the circular segments which join the :sides I0permit rotation of members fitted thereon. If desired, a plurality ofinwardly extending striated ribs I2 may be formed in the side wall orperipheral portion of.the1crown-f 5. As-shown, the ribs I2 taperinwardly as they approach the crown .end'of Whichtheyzarejoined. Theribs .I2 performthe Vimportantifunction .oflincreasing the strength andrigidityofthe crown 5.

The flange 8 of the'mountingfsleeve'S is, preferably of a form whichvmay bebroadly described as corrugated. There are'a'plurality of radialchannels I3 which, likefthe ribs I2, may conveniently be formed insymmetry with the sides of the hexagonal wall of crown'5. Intermediatethe channels I3, a plurality of radial striated and axiallytapered ribsI5 may be formed in such a manner as to provideon' the outermostperipheral portion of the flange 'aplurality of annular segmentalsections I6 which are-'closer to the end .of crown-5 than any .of theother parts of the flange 8 (Fig. .12). The upraised webs oneithersideaof the vribs I5 between the ribs and the channels 1|'3 mayhave apertures I1 formed therein-and theichannels I3 may be providedwith longitudinal aperturesIS located on a somewhat largerdiameter.

It will be evident to those in the art that the sleeve 3 is well adaptedto large scale production. It caribe completelyformed fromsheet metal bya series of drawing and pressing or stamping cperations,.nolmachiningbeing necessary. Furthermore, as will become more apparent hereinafter,the dimensional requirements are not at all exactinganother featurewhich is particularly desirable in quantityproduction.

As best indicated linFig. 2, the crown end of the mounting sleeve '3 is.'xedly'connected to .a housingor `backing iplate .12| by means of bolts23 which are threaded in the spacer ring 25 that is welded at 21 to theplate 2|. The plate 2| is secured by suitable means .(not shown) to theaxleqhousing .-A .or-.the like. An annular channel 29 is formed intheplate 2 I and this serves as a cylinder for an'annularexpander tube orpiston 3| `of suitable construction. The wall of the channel 29 has anaperture l33 which receives a pressure fluidconduit-35 that deliverspressure fluid from the hydraulic brake actuating mechanism (not shown)to the underside of the piston 3|. Variations in pressure-cause movementof the piston 3| in an axial direction. Movement of the piston 3| istransmitted to a number of members vwhichiare mounted in series foraxial movement on the-sleeve 3. AThe rst of these is a'pressure plateforcam ring 31 which is in immediate engagement with the piston 3|. Thering 31 engages a disc-like braking member 39'Whichl in turn engages oneface of the disc-type brake shoe 4|. Another disc-like braking member 43may be mounted on the sleeve 3 between the opposite face of the brakeshoe 4I and the sleeve rim 8. In the preferred arrangement, which may,however, be reversed or otherwise modified, the braking members 39 and.43 are nonrotatable, being fitted to the flat sides I0 of the crown 5,and the brake shoe 4I is rotatable with the wheel or otherobject to bebraked. 'In this arrangement the cam ring or pressure plate 31 is fittedto the circular segments II of the corwn `5 and is therefore rotatableand means are provided so that "such rotation of the cam ring 31 causesaxial movement of the members 39 and -43-and shoer4| Which issubstantially equal in amount tothe loss of thickness of these parts dueto wear.

Because of this provision, it will berecognized that the stroke ofpiston 3| is substantially constant regardless of the condition of thebrake linings-orfin other words, the brake is self-adjusting.

The brake shoe 4| comprises a discv 44 which may be formedoffmetal andis preferably provided with a central aperture Y45 substantially largerthan the crown 5 of sleeve 3 and with a notched or slotted (Figs. 4, 5and 16) peripheral rim or flange 41, the brake linings 49 being rivetedor otherwise suitably secured to the radial faces of the disc 44. Theshoe 4| is rotatably connected by means of its slotted flange 41 to animpeller 5|. The impeller 5| resembles the brake drum of conventionalautomobile wheels and is thus adaptable for permanent connection to thehub of a wheel (not shown). It has a peripheral rim 53 in `which areformed a plurality of inwardly extending blades 55. The blades arepreferably'formed by inward deformation of sheared sections of the rimso as to provide a plurality of radial apertures 51 in the rim, theseapertures serving as outlets for coolant air, as will be describedhereinafter. The blades 55 of the impeller 53 fit in the notches 48 orslots in the rim of the brake shoes 4| and the brake shoe rim V41 fitsthe inner periphery of the impeller rim'53. Thus the impeller 5|rotatably supports the brake shoe and also rotates it by Virtue of thekey connection between the respective blades and slots, this connectionbeing such as to freely permit relative Yaxial movement of the shoe 4|along the crown 5 of the mounting sleeve 3.

`Braking is accomplished by axial movement ot the shoe 4I and thenonrotatable members 39 and 43. This movement results in a forcedfrictionengagement between the radial faces of these members andtheradial brake linings 49. lWhen this frictional connection is made, as aresult of axial movement caused .by the piston 3|, the rotary impeller5|, which is secured to a Wheel, is connected to the nonrotatable sleeve3 and thus to the chassis. The frictional engagement provides resistanceto rotation of the impeller 5I andthe parts attached thereto and much ofthe kinetic energy of the rotating members is transformed into heat atthis connection as braking takes place. In accordance with theprinciples of this invention, a-series of passages are provided in heattransfer relationship with the brake linings 49 and flow of coolant airtherethrough is actuated by the impeller 5| 'Ihese passages are bothaxially and radially directed, the enlarged aperture 45 of the shoe 4|providing means for the axial flow of air between it and the sleevecrown 5.

The braking members 39 and 43 are nonrotatably attached to the sleevecrown in such a manner that they also permit axial flow of air along theouter surface of the sleeve crown 5. is` shown in Fig. 8, each memberhas -a central aperture 59 that is substantially larger than the sleevecrown 5 but is provided with a plurality of inwardly extending radialprojections 6| with flat ends which fit on the flat sides of thehexagonal crown 5 to prevent relative rotation, though permittingrelative axial movement.

The braking members 39 and 43 may also provide radial passages for theflow of coolant air. This may be conveniently accomplished byfabricating these members into such a form that they may be broadlydescribed as corrugated, this construction having the added advantagesof increasing the rigidity of the members, making them adaptable tofabrication by stamping from sheet metal or the like, and most importantof greatly increasing the rate of heat dissipation and lowering thetemperatures within the brake. With respect to these features, themembers 39 and 43 may be of identical construction. Thus, as'shown inFigs. 8 and 9, the members 39 and 43, comprise discs which are formedwith radial corrugations to provide channels 93 and ridges or lands 65,the inclined surfaces appearing in these figures being formed on plate39 for the purpose of providing a self-adjusting brake as will bedescribed hereinafter. The members are provided also with a plurality ofapertures 91 which are preferably located on substantially the samediameter as the apertures I9 in the rim 8 of the mounting sleeve 3. Itmay be noted from Figs. 2, 3 and 5 that the corrugations in the brakingmember 43 t into those formed in the rim 8 of the mounting sleeve 3 sothat this interconnection serves not only to limit axial movement of thebrake member 43 in the outboard direction, but also to prevent rotationof the member 43.V

As will be observed in Figs. 2, 3 and 5, ridges 65 on one radial face ofeach of the braking members 39 and 43 are disposed to engage with theradial brake linings 49 of the shoe 4|. l The channels 63 between theridges 65 therefore define a series of radial passages or conduitshaving communication at their inner radial ends with an annular chamber69 that surround-s the crown 5 and is formed by virtue of the enlargedapertures 45 and 59 in the shoe 4| and braking members, respectively.'The radial passages so formed in the braking member 39 havecommunication at their outer radial ends with an annular chamber 'Hwhich lies between the inner and outer peripheries, respectively, of therim of housing plate 2| and the member 39. The radial passages so formedin the braking member 43 have communication at their outer radial endswith the annular chamber 13 in which the imneller blades 55 rotate aspreviously mentioned. Preferably, the chambers and 13 are separated bythe brake disc 44 so that there is no axial flow therebetween. Theradial passage forming channels B3 alternately open into theV linings 49and are separated therefrom by the thickness of the discs from which thebraking members are formed. In eithercase it is apparent that coolantflowing therethrough will receive heat resulting from frictionalengagement of the ridges 65 with the brake linings 49.

Air is the most convenient coolant medium for dissipating the heat offriction and it is preferably admitted to the brake on the inboard orplate 2| side, the impeller 5| thus being on the low pressure side ofthe system and the apertures 51 serving as outlets through which theheated air can escape. The apertures 6l in the braking member 39 receiveair through slots 'i5 (Fig. 6) which are formed in the cam ring 3l insuch a manner as to register therewith. Slots 15 rather than circularholes are preferably employed because,V as will hereinafter bedescribed, the cam ring rotates a slight amount relative to the brakingmember 39 and housing plate 2| during the life of the brake linings 49.Holes in the plate 2| admit air to the cam ring slots 15. These holesreceive air from an annular chamber 'i9 which is formed between theplate 2| and a cover 8| which is secured to the inboard radial facethereof and has bosses `82 bearing upon the plate 2| to separate ittherefrom. It has a tapered peripheral rim 83 which extends axially tooverlap the rim 53 of the impeller 5| so that these two memberssubstantially encase the brake Air from chamber 19 may also pass throughholes 89 in the plate 2| into the chamber 1| at the outer periphery ofthe braking member 39. Air flows into the chamber 19 through an inletopening 85 in the cover 8|, which may be screened, if desired. A mudshield 81 may be provided on the cover 8| to guide air so that it mustflow in a substantially circumferential or `tangential direction toreach the opening 95. By virtue of this arrangement the air in annularchamber 19 is in rotation so that any particles of dust carried therebywill be thrown radially outwardly against the rim 93 of the cover 8|from whence they can escape from the brake through the annular space 39between the rims 83 and 53.

Before proceeding to a description of the wear compensating adjustmentembodied in the structure shown in the drawings, the manner in whichthat structure operates which has already been described will bediscussed. During the period in which no braking is desired, theimpeller 5! rotates with the wheel and by virtue of its interconnectionwithv the impeller blades 55 the brake shoe 4| also rotates. Pressurehas been released on the annular piston 3| so that the axially disposedcompression springs 9| of a suitable f-orm (Fig. 17) which are affixedat 99 to the sleeve crown 5 and bear upon the radial projections 6| onbraking member 39, may force the braking member 39 axially inboard toexpand the assembly of braking members and brake shoe 4| and prevent anysubstantial frictional engagement between the cooperating faces of thebrake shoe and the members.

When it is desired to brake and pressure is increased on the bottom ofthe piston 3 l, it moves axially outward and forces the cam ring 3?, thebraking members 39 and 43, and the brake shoe to move axially in thesame direction. The limit of this movement before braking occurs isdefined by the rim 8 of the mounting sleeve 3. When the parts are forcedagainst this rim, the normal force between the ridges 65 and the linings49 causes the braking members 39 and 43 to frictionally engage the brakeshoe 4| to dissipate rotative energy in the form of heat wherebydeceleration occurs at a ratevdependent upon the applied normal forces.

During this period of deceleration, the impeller 5| functions to lowerthe pressure in chamber 13 so that air is drawn through the brake toeifectively remove a substantial amount of the f-rictional heat created.This air enters the chamber. 'I9 through; Opening 8.5, inthe manner justindicated. so that dust particles are centrifugally separated therefrom.A portion of this air flows axially through holes 80 in the plate 2|into the chamber 1| and thence radially inwardly through the channels63` in braking member 3 9to the central annular chamber 69. This airtherefore removes heat from the inboard brake lining 45t-and themember39. The remainder of the air in chamber 19 -flows radially inwardly toholes 11 in plate 2| and thence axially through slots 15 in the cam ring31 and holes 61 in the brake member 39 to the inner radial end ofchannels 63 in the member 39 whereupon it; mixes withthe other portionofthe air passing throughthese channels and flows into chamber 69.Thisintermixture of the two portions of air lowers the temperature ofthat portion which has passed radially inwardly from chamber 1| so thatthe resulting mixture is capable of enicientlyv removing heat from theoutboard lining.r 49andthe brakejmemberg. This isaccomplished as airfrom chamber 69,1ows radially outwardly in the channels 63 to thechamber 13-from whence it passes through apertures 51 toatmosphere.Instead of followingthis path, air in the chamber B9 may flowthrough theholes I1 in the rim 8- (Fig. 5) or through themating holes 61 and I9 inthe brakingmember 43 and rim 8 and thenceradally outwardly to the outletapertures 51.

While the heaty removing action of the-l air inflowingthrough the brakeI during operation thereof results in a substantial decrease in the rateof wear ofthe linings 49, wear inevitably occurs and it isa furtherfunction of the structure shown in the drawings to automaticallycompensate forl such wear so that the required axial movement of thepiston 3| and other parts to effect braking is substantially constant.In order to accomplish this self-adjustment, cam means are preferablyusedand may be provided between the cam ring 31 and-the braking member39 to increase the eective overall axial length of these parts whenengaged in an amount substantially equal to thedecrease in the overallaxial length (orthickness) o f the members 39 and 43 and brake shoey 4|because of wear of the radial faces thereof. Inother words, the cammeans operates to maintain substantially constant the overall length ofthe parts between plate 2| and the rim 8 -of the mounting sleeve- 3.

For this purpose, the braking member-39, asv

shown in Figs. 8 and 9, is provided with' a plurality of cam tracks 95which are axially tapered in a circumferential direction. These tracksrise from the channels 6 3 to the ridges 65 and, like theotherfeaturesof construction already described inconnection With the braking'members39 and 43, may be formed in a suitable blank disc of metal by pressingvor stamping.

The cam ring or pressure plate 31 (Figs. 6 and '7)l comprises a discwhich has a plurality of cams 91 formed therein which t in thecam tracks95 as shown in Fig. 3.. The cams 91 may be formed by a drawingvoperation on the disc and it will be recognized that theyv have a commonshape which is thesame as that of the cam tracks 95. Rotation of the camring 31 in one direction (clockwise when viewing Fig'. 3 from the right)willvforce the cam ring and the braking member 39 apart or increasetheir overall axial length. The ring has an annular flange orrim 98 -onitsinneriperipherywhich is adapted 81 tot; the. c ircu1ar por t1ons AlV| of the crown 5 -and rotate` thereon.r The rim may be provided withsuitable` cutouts 98 to receive the projections 6| on thebraking member39, these cutouts being sufficiently long to allow a limited amount ofrotation of the ringg31.

It will be evident that the cam means must include actuatingmeans forrotating the ring- 31 in response to a decrease in thickness of the shoe4| or members 39 and 4-3. One means for accomplishing such rotationcomprises a plurality of resilient pins 99 which are pinned to fixedpoints bvmeans ofrivets |0| which connect the outboard ends of the pinsto the side wallof the sleeve'crown 5. The pins extendaxially, but notlie in planes throughthe axis of the brake i. e.A they also extendcircumferentially of the axis. The free ends of the pins 99 are taperedto lit or wedge in the sides ofa V- shaped annular groove |02 whichisformed in the cam ring 31, this fit being such that when the pinsand'groove |92 are so engaged, thereis nov rotation ofthe ring 31relative to the pins 99 in the counterclockwise direction. Reference toFig. 2O will enable it to be readily recognized that, when thisengagement of pins and groove occurs, axial movement of the ring 31, dueto pressure on the piston 3|, will be accompanied by rotation thereof.This is the case because the pins 99 must ilex about points |0| withboth axial and circumferential components of movement as defined by thearc |03 (Fig. 3). This circumferential component is transmitted to thering 31 and causes rotation thereof in the clockwise direction to spreadit and the braking member 39. When the pressure on piston 3| isreleased, the springs 9| force the member 39 and ring to-moveaxiallyinwardly toward plate 2l.

Thelength of the pins 9-9 isadjusted so that in initial assembly thepins 4do not rotatively engage the grooveY |02funtil the members 39 and43 and the brake shoe 4| are in tight braking engagement. i. Inotherwords the plane defined by thefree ends of the fingers 99 is spaced fromthe p1atev31 by-the amount of slack clearance when the brake isdisengaged. Thus, so long as there isf no wear of the linings 49, thecam ring 3,1 has only simple axial movement when brake pressure isapplied thereto throughthe piston 3|. When, however, some wear occurs,the required axial l.movement of the cam ring 31 is increased by `theamount-'of such wear. As the ring 31 attemptsto movethrough this axialincrement, it applies force-to .the pins 99 which bendsubstantiallyalong arc-|03 about their rivet connections |0| and byvirtue of their engagement with the groove- |02 rotate the ring 31. Thecams 9 on the ring- 31 therefore ride along the cam tracks toaxiallymove the braking member 39 relative tothe cam ring 31. Thus, the axialincrement of increased movement required of the member-39 before itengages the brake shoe 4| isI accomplished in part by axial movement ofthemember 39 with the ring 31 and the balance by axial movement of themember 39 relative to ring 31 due to the action of the cams. The part orcomponent of the'axial increment accomplished by movement ofl thefmember39 jointly with the ring 31 represents the -amount by which the brake isstill out of adjustment. On the next application of the brakev pressure,however, the operation just described will be repeated with the resultthat the ring 31 will be rotated by the pins99 and the member 39 willmove relatively to the'ring 31' to-reducethe axial componentbyk evidentthat in practical effect the cam means,

operates to maintain a substantially constant disengaged clearancebetween the braking members 39 and 43 and the brake shoe 6|.

In order to overcome the tendency Aof the pins 99 to rotate cam ring 31in the counterclockwise direction when they flex back to their normalpositions, a ratchet connection may be used between the ring 31 and thesleeve crown 5. This comprises several sets of ratchet teeth |05 formedon the inner periphery of the ring and suitable pawls |01 riveted to thecrown 5. It will be apparent from Figs. 4 and 18 that though the pawls|01 will permit ring rotation in the clockwise orexpanding direction,they will engage the teeth |05 to prevent counterclockwise rotation.

In a modied form of means for rotating the ring 31, the pins may be usedtoo as ratchet pawls. As shown in Fig. 7A, the pins 99 are pointed so asto engage the ratchet teeth |05 and the latter are arranged so that theends of the pins will seat therein to rotate the ring 31 in a clockwisedirection. Relative movement in the counterf clockwise direction ispermitted, however, by the slanting parts of the teeth |05', it beingappreciated that when pressure in piston 3| is released the force ofreturn springs 9| makes the contact of pins 99 on teeth |05' relativelylight so that the pins 99 are able to move from one tooth to another aswear occurs.

It is often desirable to be able to lock the braking members 39 and 43and the brake shoe 4| together, as, for example, when parking a carembodying brakes of the type herein described. Mechanism foraccomplishing this is shown in Figs. `13--15 and includes a radial ear||0 on the outer periphery of the cam ring 31 which extends through asuitable slot in the backing plate 2|. It will be evident from thepreceding description that by forcing theear to the left in Figs. 13 and19 that the ring 31 will be rotated so that its cams 91 force thebraking members 39 and 43 to tightly engage the brake shoe 4|. Themember ||2 serves as a link which may be connected to the parking brakehandle (not shown) whereby force may be applied to lock the brake. Thelink l|2, which is above the cover 8 I, has a bifurcated end (Fig. 15)which is pivotally connected by means of a pin ||4 to an arm |15. Atension spring IIB is inserted between the pin ||4 and a pin ||1 that isaixed to the cover 8| to yieldably resist movement of the link ||2 tothe left. The arm extends inwardly through a suitable aperture in thecover 8| and is pivotal- 1y connected by means of a pin ||8 to the sidesof. an elongated U-shaped bracket |20 which is adapted to slide or movecircumferentially on or justabove the outer periphery of the rim ofplate 2 l, and is yieldably prevented from counterclockwise movement bya tension spring |2| attached thereto and to a suitable ear |22 on thestationary plate 2|. The lower periphery of the arm comprises a camsurface |23 which has an increasing radius forward from the pin ||8. Thebracket may have a ridge |24 formed in 10 the bottom thereof whichcooperates with the cam |23 to forma pincers for fixing a tongue |26,which is received therebetween, to the bracket |20. The tongue |26 ispivoted at |28 to the ear `|10.

When the parking brake handle is actuated to pull link ||2 to the leftin Fig. 13, the lever or arm ||5 pivots about pin H8 so that the camsurface |23 securely clamps the tongue |26 to the ridge|24 on channelbracket |20. Continued movement of the link ||2 causes the clampedassembly comprised of tongue |26, bracket |20 and arm ||5 to move to theleft. This rotates the cam ring 31 and applies the brake. The mechanismis locked in this position by means of a conventional locking device onthe brake handie (not shown) which resists movement of the link l2 tothe right. When it is desired to free the brake, the link |2'is unlockedand the spring |2|, which is stronger than spring I6, pulls the clampedassembly to the right. This movement continues until an ear |30 on thebacking plate 2! strikesthe bottom of a slot (not shown) in which itrides that is in the channel bracket |20. Springv HG then rotates thearm H5 in the clockwise direction until a flat |32 on the cam |23engages a stop |34 on the upper side of the bracket |20. This freesvthetongue |26 so that the cam ring 31 is free to rotate under the influenceof the pins 99 as previously described.v It will be evident uponconsideration of the action of the ratchet teeth |05 and pawl |01 andtheteeth |05V and pins 99 that these ratchet means should not be usedwith the parking brake mechanism just described since they will preventthe ring 31 from rotating back to the position it occupied before thebrake was applied. It is desirable, nevertheless, to provide means forpreventing undesired backward rotation of the ring 31 and this can beconveniently accomplished by means of the tongue |28. For this purposethe tongue |26 is provided with a series of serrations or ratchet teethv|36. `These teeth are engaged by a pawl |38 which'may be secured byrivets or other suitable means to the lever arm H5. It will be apparentrfrom Fig. .13v that the pawl |38 engages the teeth |36 lto preventmovement of the tongue |26 to the right or movement of the ring 31 in adirection to reduce the `clearance between it and member 39. When theparking brake is actuated, the pawl |38 may become disengaged from theteeth |36, but its locking action is not required during this periodsince the cam |23 fixedly clamps the tongue |26 to the bracket |20 whichhas a fixed rotary position defined by theear |30.Y v Y, v It will nowbe recognized that the brake of the present invention may beeconomically manufactured ksince all of the major parts, exclusive ofthe parking brake mechanism, may be fabricated from sheet metal bysuitable press operations. The corrugated construction of the brakingmembers 39 and 43, in particular, greatly increases their strength and,because of the resulting increased surface area it greatly increasestheir ability to radiate heat. In heat dissipating properties thesebrake members. are about twice as efficient as conventional brake discsformed from the same gauge metal. Due to the interrupted radial facesresulting from the formation of channels 55, much higher unit brakingpressures may be employed than heretofore without danger of burning thelinings. The cooling system employed with the corrugated constructionalso serves to increase the rate of heat dissipation.

As a result of these features the brake of the.

specific details illustrated, without departure from.

the principles thereof.

What is claimed is: f

1. A rotary brakeconstruction comprisinga xed support, a rotatable brakeshoe member mounted on the support having avradial friction surfacethereon, a disc member mounted on the support having a radial surfacefor engagement with the brake shoe surface, said brake shoe member beingrotatable with the object to be braked andthe other member beingnon-rotatable but axially movable, a movable actuator on the support foraxially moving the members, means whereby rotation of the actuatoraxially moves said disc member, and a fixed length flexible membersecured tothe support and engageable with the actuator for rotating thesame upon relative axial movement between the actuator and support. 1

2. The invention as claimed in/claim 1 wherein` the fixed lengthmembervis obliquely disposed with respect to the rotary plane of theactuator and has one end fixed and a free endengageable with theactuator.

3. A rotary brake construction comprising a rotatable brake shoe member.havingv a radial friction surface thereon, a discmember having a radialsurface for engagement with the brake shoe surface, one of'said membersbeing rotatable with the object to be braked and the other non-rotatablebut axially movable, a movable actuator for axially moving the members,power operated means for axially but non-rotatably moving theactuator toeffectuate braking, means fy whereby rotation of the actuator axiallymoves said disc member, a flexible member engageable with the actuatorfor rotating thesame in one direction upon axial movement thereof in onedirection, and ratchet means for preventing rotation of the actuator inthe opposite direction.

4. A rotary brake construction comprising a brake shoe member havinga'radial friction surface, a memberfor braking engagement with the brakeshoe member, one of themembers being rotatable with the object to bebraked, one' of the members being axially movable into engagement withthe other, anactuatormember for rmoving the last-mentioned member, saidAactuatormember and last member being capable of i relativeaxial androtary movement, power operatedmeans for axially but non-rotatablymoving the actuator to effectuate braking,-A means whereby relativerotation ofthe actuator and last member causes axial movement of`themember, and a rotator for one. of the last two mentioned members. forcausing such relative: rotation. andoperatedv upon predetermined axialmovement of such member relative .to a fixed point.

5. A rotary brake. construction comprising a.k

brake shoe member having a radial friction surface thereon, a disc.member having a radial surface for engagementfwith the brake .shoesurface, one of said members .comprising the rotary member to be braked.and the other-.comprisingthe braking member, one of said members beingAaxially movable, a pressurefdisc member capable of force transmittingengagement with one surface of the axially movable member formoving theopposite surface into engagemer'itv with the" otherimember, poweroperated meansfor Aaxiallyy but. non-rotatably moving the members toef-4 fectuate braking, and automatic means for increasing the overallvaxial length of the engaged; l disc `and member in amountssubstantially equal to decreases in the overall axial length of theengaged members, said means including cam means operated vupon saidldecreases in length to spreadY said disc and member.

6. A rotaryl brake construction comprising". a brake shoe member havinga radial friction-surface thereon, a disc member having a radialsurface4 for engagementr with the brake shoe surface,

one of said members being rotatable with the object-to be braked.andtheother non-rotatable but axiallyr movable, a pressure disc member capableof axial movement and force transmitting.'H

engagement `withvone surface of the axially movable member for movingthe opposite surface intor engagement with the other member, poweroperated means for axiallyy butr non-rotatably moving the members toveffectuate braking, cam-il means between the pressure discvmemberandfaxially movable member forgoverning. the overall axial` length thereof,and means actuated upon adecrease in the thickness of the. brake shoefor operating the cam means to increase said length in Aan amountsubstantially equal to said decrease in the thickness or axial length ofthe brake shoe, said-meansincluding al resistor@ normally out ofoperative lengagement with said axially movable membersbutengaged byone-off said axially movable members upon decrease in face, one ofsaidmembers comprising the-rotarymember to be braked and-the othercomprising thebraking member, one of said members being axiallymovable,- a pressure -disc member capa-4 ble of force. transmittingengagement with one.

surface of the axially movablevmemberl for-movingthe opposite surfaceinto engagement-with the'A other member,r power operated meansfor-Vvaxially but non-rotatably moving the members to l effectuate braking,saidpressurey disc being rotatable, means operable by-rotation of thediscl in-onedirection for moving` the axially movable member toward thebrake shoe member, and means responsive to -wear of -the vradiallsurfaces forlrotating s aid :disc in an amount proportional to saidwear.V

f 8'.I Af. rotary brake-:construction comprising a brake shoe-memberhaving a-radial friction-surface '-thereon; a disc member having aradial survface for engagement with the brakeshoe sur-1` face, one-ofsaidmembers comprising the-rotary*` member to be braked and theothercomprising the braking,l member, one of saidmembers being axiallymovable, a pressure discy member capafY ble'oflforcetransmittingengagement with one surface ofthe axially movable memberAfor mov- .ing thev opposite surface into engagement with thefothermember, power operated means' for axially but non-rotatably'moving themembers to effectuate braking, said pressure disc being` rotatable,means operablenby rotation ofthe discA in one direction formoving themember toward` the Aother member, and meansseparate from said poweroperated 'means for rotating` thediscinan amount proportional to an increasegin axial movementl required-between successive engage-A mentsto-engag'e-the members. A y

9. A brake construction comprising a pair of members having radialfrietional engaging faces, one of the members being rotary and the otherstationary, means for engaging and disengaging the members to effectbraking, means providing radial passages in the members for the flow ofair therethrough, common means for rotating the rotary member andcausing flow of air through said passages, a cover including an annularrim surrounding the members and providing a chamber for air incommunication with the passages, and means for admitting air to thechamber in a direction tangential to the rim whereby centrifugalseparation of solid particles from the air is effected in said chamber.

10. A rotary friction brake comprising a support member adapted forfixed connection to a non-rotatable object, said member having asubstantially flat sided outer circumference, a brake shoe havingopposite radial friction faces disposed on the member for rotary andaxial movement relative thereto, braking members on opposite sides ofthe shoe having circumferentially spaced projections fitted to the natsides of the member, means for axially moving the braking members toeffect friction engagement thereof with opposite sides of the brakeshoe, and springs affixed to the flat sides of the support member andengagea-ble with the projections for yieldably separating the brakingmembers and shoe.

11. A rotary friction brakecomprising a support member adapted at oneend for fixed connection to a non-rotatable object and having a radialoutwardly extending flange at the other end, the central portion of saidmember having a substantially flat sided outer circumference, a brakeshoe having opposite radial friction faces disposed on the member forrotary and axial movement relative thereto, braking members on oppositesides of the shoe having circumferentially spaced projections on theinner peripheries thereof fitted to the flat sides of the member, apressure member mounted on the support member remote from the flange andadapted upon movement in the direction of the flange to force themembers and shoe thereagainst to effect braking, means whereby rotationof the pressure member causes axial movement of the members toward theflange, flexible actuator members secured to the iiat sides andextending between said projections and engageable with the pressuremember to cause rotation thereof, and springs affixed to the fiat sidesof the member and engageable with the projections to yieldably resistmovement toward the ange.

12. A rotary friction brake comprising a support member adapted at oneend for fixed connection to a non-rotatable object and having a radialoutwardly extending corrugated flange at the other end, the centralportion of said member having a substantially flat sided periphery, abrake shoe having opposite radial friction faces disposed on the memberfor rotary and axial movement relative thereto, a rotatable flowactuating impeller, said brake shoe being mounted on the im-peller forrotation therewith and axial movement relative thereto, radiallycorrugated braking members on opposite sides of the shoe havingcircumferentially spaced projections on the inner peripheries thereoftted to the flat sides of the member, said brake shoe and brakingmembers defining a chamber around the flat sides of the support member,having fluid communication with the channels formed in the corrugatedbraking members, said braking member corrugations having uidcommunication with said impeller whereby the Vimpeller actuates owthrough said chamber and members, a pressure member mounted on thesupport member remote from the flange and adapted upon movement in thedirection of the flange to force the members and shoe thereagainst toeffect braking, means whereby rotation of the pressure member causesaxial movement of the members toward the flange, flexible` actuatormembers in said chamber secured to the fiat sides and extending betweensaid projections and engageable with the pressure member to causerotation thereof, and springs in said chamber affixed to the fiat sidesof the member and engageable with the projections to yieldably resistmovement toward the flange.

13. The invention as claimed in claim 11 wherein the support memberincludes cylindrical segments joining the edges of the flat sides andthepressure member is rotatably mounted on said segments.

14. A support member for disc-type brakes having axially movable brakingmembers engageable with a radially friction faced brake shoe membercomprising a sleeve having a substantially flat-sided outercircumference to non-rotatably support certain of said members, andprovide chambers between the flat sides and such cylinder as maysurround the periphery, said sleeve being adapted at one end for fixedconnection to an object and having a radial outwardly extending flangeat its opposite end, said flange serving as a xed abutment to limitmovement of the members mounted thereon in one direction when brakingforces are applied thereto in said one direction.

15. 1n a disc brake construction, the combination of a brake shoe disc,a braking disc for engagement with the brake shoe disc, an actuatormember operatively connected to one of the discs for moving the discsinto engagement, said member being movable axially to effect discengagement, a pressure actuated piston for axially moving the member toengage the discs, said member having a cam surface thereon, one of saiddiscs having a complementary cam surface engaging the member cam surfacewhereby rotation of the member moves said one of the discs toward theother, means actuated when there is wear of the brake shoe for rotatingthe member to take up the loss in thickness due to wear and therebymaintain the overall length of the discs and members and the clearancetherebetween substantially constant whereby said piston has asubstantially constant stroke despite wear of the brake shoe.

16. In a disc brake construction, the combination of an impeller havinga radial face adapted for driven attachment to a wheel and a circularcircumferential flange with radially inwardly extending fan bladesformed therein, a circular disc having a circumferential flange fittinginside the impeller flange, said disc ange having notches thereinreceiving said blades whereby a keyed rotary connection is effectedbetween the impeller and disc, and brake lining in a radial face of thedisc whereby it comprises a brake shoe.

17. In a disc brake, a brake operator which operates axially and appliesan axial force, a support for reacting against said axial brakeoperating force, annular braking members radial to said force movablymounted between and operatively connected to said operator and support,

"vi/hereby radial faces of said members are pressed together to eectbraking upon application by the operator of an axial force and wear ofsaid radial faces has a tendency to increase the stroke of saidoperator, means for overcoming said tendency and maintaining asubstantially constant operator stroke comprising an adjustable membermounted between said operator and support in axial force transmittingalignment with the braking members, said means being of an ad'- justableeffective axial length and adjusted in said length by adjustment of saidmember, and a movable adjuster for said adjustable member to increasethe effective axial length of said means by amount corresponding to thewear of said radial faces, said adjuster being effectively disconnectedfrom said members during a predetermined normal operator stroke butengageable with the adjustable member and movable upon increase instroke to eiectvv said increase in member length.

18. In a disc brake the combination of a first rotatable member to bebraked, a second braking member operatively engageable with the firstmember to effect braking, one of said members being axially movable toeffect such engagement, return spring means urging said members out ofoperative engagement, there being a predetere mined slack clearancebetween said members, a reciprocable brake actuating element having aVpredetermined operating stroke beginning at a predetermined position,connecting means operated by the element and transmitting force andPHIEILP'u SM. Fny ER.

References cited 1n the fue of this 'patent UN-i'rED STATES PA'IYENTSNumber v Name Date 1,525,568 Chapin Feb. 10, 1925 l1,566,569 Anderson ir Dec. 22, 1925 1,604,060 Matthews Y 1`Oct. 19, 1926 1,740,993 McDonnell1 Dec. 24, 1929 1,950,381 BartZ V v Mar. 13, 1934 1,989,179 Versluis 1 1Jan. 29, 1935 2,024,328 Batie 1 7; 1 Dec. 17, 1935 2,031,742 Smith etal.1e- Feb. 25, 1936 2,095,094 Glasne'r' 11;- Oct. 5, 1937 2,109,637Gtkaiss 1 Mar. l, 1938 2,165,978 Miller July 11, 1939 2,317,599 Frer -1Apr. 27, 1943 2,384,297 Goepfiich Sept. 4, 1945

